Single or multi-track fluid bearing heating apparatus and method

ABSTRACT

Apparatus and method for transporting articles, such as silicon and like wafers employed in the manufacture of semiconductor devices, on a track between two predetermined stations and past a heating station. The transport means utilized for the track comprises a positive drive belt and a pair of fluid bearing track structures for supporting the articles and moving the same in conjunction with the belt, preferably while the articles are rotated during movement past the heat source to insure uniform article heating. In the preferred embodiment, the apparatus comprises a plurality of parallel tracks each defined by a belt and fluid bearing track structure synchronously actuated for moving a plurality of parallel streams of wafers simultaneously past the heating station.

United States Patent Flint Mar. 11, 1975 1 SINGLE 0R MULTl-TRACK FLUID BEARING HEATING APPARATUS AND Prim ry Examiner-J hn J- Cam y METHUD Attorney, Agent, or Firm-Flehr, Hohbach, Test,

Albritton & Herbert [75] Inventor: Alan G. Flint, San Jose, Calif. [73] Assignee: GCA tlorporation, Bedford, Mass. 57 ABSTRACT [22] Filed: Apr. 3, 1974 Apparatus and method for transporting articles, such as silicon and like wafers employed in the manufac- [211 App1'N0"457432 ture of semiconductor devices, on a track between two predetermined stations and past a heating station [52] US. Cl 432/11, 432/124, 432/235 The transport means utilized for the track comprises a [51] llnt. Cl. F27b 9/14 positive drive belt and a pair of fluid bearing track [58] Field of Search 432/11, 124, 235; 302/2 R, structures for supporting the articles and moving the 302/30, 31 same in conjunction with the belt, preferably while the articles are rotated during movement past the heat [56] References Cited source to insure uniform article heating. 1n the pre- UMTED STATES PATENTS ferred embodiment, the apparatus comprises a plural- 2,605,091 7/1952 Socke 432 11 itY of Parallel tracks each by a and fluid M63134 12/1964 Stanford I I I I H 432/1] bearing track structure synchronously actuated for 1184224, 5/1965 Shelley g 3 1 moving a plurality of parallel streams of wafers simul- 3 627183 12/1971 Hittner v 432/11 taneously past the heating station.

313313;; 511333 52121171;:11:111113113111.......::1:: 383/3 37 Claims, 10 Drawing Figures PATENTED MARI l 975 SHEET 1 BF 5 PATENTEB NARI I I975 saw 3 u; 5

- BEUUBGUHBEBEDUHE SINGLE OR MULTI-TRACK FLUID BEARING HEATING APPARATUS AND METHOD CROSS REFERENCE TO RELATED APPLICATION In Cecil A. Lasch, .lr. copending application Ser. No. 203,086, filed Nov. 25, 1971 entitled Fluid Bearing Transfer and Heat TreatingApparatus and Method, an apparatus and method are disclosed for transporting articles at varying rates through a heat zone utilizing a fluid bearing. Such application does not, however, utilize the positive drive and article rotation procedures and related features disclosed herein. The apparatus and method of said Lasch, .lr. application are designed to produce improved results and solve handling problems in a heated atmosphere which are different from those confronting applicant herein.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to the field of transporting articles. More particularly, this invention relates to the field of moving articles between predetermined stations and past a heating station at which the temperature of thearticles being transported is uniformly elevated for previously known treating purposes.

Still more particularly, this invention relates to the field of handling and transporting fragile articles, such as silicon and like wafers commonly utilized in the electronics industry in the manufacture of semiconductor devices, and for uniformly heating such wafers during manufacturing procedures thereon utilized to convert such wafers into semiconductor devices.

Still more particularly, this invention relates to the field of wafer transportation means which utilizes a track defined by a combined fluid bearing positive drive pacing belt structure, and the method for transporting wafers between predetermined stations during the manufacture of semiconductor devices from such wafers.

While the specific aspects of the transportation apparatus disclosed herein relate to the improved and combined fluid bearing and positive drive handling and transporting of wafers utilized in the manufacture of semiconductor devices, and is so disclosed hereinafter, its applicability to other fields in which articles are required to be transported under controlled non-manual positive drive conditions also should be recognized.

Description of the Prior Art Fluid bearing track structures of various types have been generally known heretofore and the following patents disclose devices and structures which are exemplary thereof: Hazel U.S. Pat. No. 2,778,691 dated Jan. 22, 1957', Cole U.S. Pat. No. 3,l03,388 dated Sept. 10, 1963', Coville U.S. Pat. No. 3,318,640 dated May 9, 1967; Lasch, Jr. et al. U.S. Pat. No. 3,645,581 dated Feb. 29, 1972; and Lasch, Jr. U.S. Pat. No. 3,7l8,37l dated Feb. 27, 1973.

Additionally, the aforementioned Lasch, Jr. application Ser. No. 203,086 illustrates and describes a fluid bearing utilized in conjunction with a heating mechanism, and other prior art cited thereagainst relates generally to fluid bearings for transporting articles, both in ambient and heated atmospheres.

While fluid bearing track structures have been disclosed in the noted patents and application, none of such patents or application discloses or describes the improved combination of a fluid bearing track structure and cooperating positive drive pacing belt incorporating therein the improved structural and wafer handling features of the present invention. So far as is known, the apparatus and method of this invention have been unknown heretofore, particularly in conjunction with the transportation of fragile wafers between predetermined stations past a heating station.

SUMMARY OF THE INVENTION The present invention relates to an improved single or multi-track heating apparatus and method. More particularly, this invention relates to an improved apparatus and method for supporting a single stream or plural streams or articles on a fluid base, and spacing individual articles from each other while the same are paced by a positive drive pacing belt engaged with successive articles in each of such single or plural streams. In the preferred embodiment disclosed herein, a multistream apparatus is disclosed in which a plurality of parallel streams of articles are transported in synchronization to and past a treating station between in-feed and out-feed stations of the apparatus.

Still more particularly, this invention relates to a combined fluid bearing track structure positive drive belt structure by means of which flat fragile wafers are transported to and past a heating station in a generally straight line path without requiring manual contact.

Still more particularly, this invention relates to an improved heating apparatus and method by means of which streams of wafers utilized in the manufacture of semiconductor devices are carried at predetermined paced rates to and past a heating unit; in conjunction with such movement, each of the wafers preferably is continuously rotated as the same is exposed to the ele vated temperature of the heating element so that uniform heating of each wafer is insured.

From the foregoing it should be understood that objects of this invention include: the provision of an improved apparatus and method for transporting articles. such as fragile semiconductor wafers, between prede' termined stations; the provision of a combined handling track defined by an improved fluid bearing track structure positive drive pacing belt structure in combination for moving articles between predetermined stations; the provision of an improved apparatus and method for heating articles while positively transporting the same relative to a heating source; the provision in an improved heating apparatus and method of means for continuously rotating the articles being subjected to heat during movement past the heating element to insure uniform heating of each article; the provision in a fluid bearing apparatus of fluid bearing track structures having supporting fluid emanating in opposite directions from adjacent track structures to effect rotation of articles supported thereby; and the provision of improved procedures for handling and transporting articles relative to a heating station utilizing combined fluid bearing and positive drive techniques.

These and other objects of this invention and various aspects thereof will become apparent from a study of the following detailed description in which reference is directed to the attached drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view ofa multi-track apparatus of this invention.

FIG. 2 is a vertical sectional view through the apparatus taken inthe plane of line 2-2 of FIG. 1.

FIG. 3 is a vertical sectional view, on an enlarged scale, taken in the plane of line 33 of FIG. 2.

FIGS. 4A and 4B are horizontal sectional views (comprising continuations of each other) taken in the plane of line 4-4 of FIG. 3.

FIG. 5 is a vertical sectional view taken in the plane ofline 5-5 of FIG. 3 illustrating details of construction of the positive drive belt utilized in the subject apparatus.

FIG. 6 is a vertical sectional view through one track of the apparatus taken in the plane of line 66 of FIG. 4A.

FIGS. 7 and 8 are vertical sectional views through a track taken in the planes of lines 77 and 8-8, respectively, of FIG. 6.

FIG. 9 is a diagrammatic view of the pneumatic system utilized in conjunction with the illustrated embodiment of the multi'track apparatus disclosed herein.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawings and description contained herein detail features of a multi-track article transporting and heating apparatus. It should be understood, however, that the unique features of this invention are applicable to and may be utilized in conjunction with a single track apparatus, or an apparatus having more or less than the four tracks illustrated without departing from the spirit or scope of this invention. Therefore, it should be understood that constructional details presented herein are applicable to single or plural track units fabricated to meet the wafer handling and treating requirements of a particular customer.

Preliminarily, it should be understood that the subject apparatus utilizes conveyor track means which combines a linear fluid bearing with a positive drive pacing conveyor belt which controls the speed and movement of articlesbeing supported by and transported on the fluid bearing to and pasta station, such as the heating station of the illustrated apparatus. As a result, the total heat treating time of the articles may be precisely controlled. Additionally, as detailed hereinafter, preferably the articles being transported are continuously rotated during exposure to the heat source to insure uniform heating thereof in a procedure heretofore unknown.

Reference herein to wafer handling and heating is exemplary of a preferred utilization of this invention but other articles also may be handled by the subject apparatus as needs dictate.

The fluid utilized to support wafers during movement through subject apparatus may vary, depending upon the nature of the water treatment effected therein. In conjunction with the heat treating effected by the subject apparatus, nitrogen preferably is utilized as the article levitating and transporting fluid.

The preferred embodiment of the illustrated apparatus is generally designated 1 as seen in FIG. 1 and comprises three principal sections or stations, namely, an infeed end or station 2, a central or heat treating station 3, and an outfeed end or discharge station 4. It is between the infeed station 2 and the outfeed station 4 that wafers W are transported past the heating station 3 at a predetermined rate as will be described.

It should be understood that the illustrated apparatus may be self contained, as illustrated in the attached drawings, in which a plurality wafers are inserted in carriers at the infeed station 2 and are removed in groups in carriers at the outfeed station 4 upon completion of the heat treating step thereon. However, the subject apparatus also is adaptable to be interfaced directly with other apparatus utilized in the manufacture of semiconductor devices so that wafers may be fed sequentially directly to the infeed station from another apparatus and/or directly from the outfeed station 4 into another apparatus without intermediate storage or handling in groups in wafer carriers. However, for simplicity of illustration herein, the subject apparatus is illustrated as being self contained as described.

As noted from FIGS. 1 and 2, the illustrated apparatus is multi-track in construction and is defined by a plurality of discrete parallel tracks, four in number in the illustrated embodiment, designated 6, 7, 8 and 9 respectively. Hereinafter details of each track construction will be set out with respect to an individual track but it should be understood that such details are applicable to all tracks utilized in the apparatus. The plural tracks are operated synchronously to move parallel streams of aligned correspondingly spaced wafers W to and past the heating station 3 between the infeed and outfeed stations 2 and 4.

As noted from FIG. 1, the infeed station 2 is defined by a plurality of wafer feeding mechanisms, designated 11, 12, 13 and 14 respectively, from which individual wafers W are discharged in sequence onto associated tracks commencing at such feed mechanisms. In that regard, as mentioned previously, the feed mechanisms to be described could be eliminated and wafers could be sequentially positioned on the respective tracks directly from other semiconductor manufacturing apparatus. In the illustrated embodiment, however, the respective feed mechanisms are utilized which include carriers or feed magazines [6, 17, 18 and 19 respectively. Each magazine is supported for downward sequential indexing so that the lowermost wafer in each magazine may be sequentially removed therefrom and placed on an associated track as required in the treating procedure.

At the outfeed station 4, four wafer receiving mechanisms, designated 21, 22, 23 and 24 respectively, are provided for receiving wafers W discharged thereto from the associated tracks. In that regard, wafer receiving carriers or magazines 26, 27, 28 and 29 are supported by the respective receiving mechanisms for indexing sequentially upwardly upon receipt of individual wafers sequentially therein.

It should be understood that the four tracks of the illustrated apparatus are intended for synchronous operation pursuant to which full magazines each containing a predetermined number of wafers therein, such as twenty-five, are positioned on the respective feed mechanisms. The feed magazines are sequentially emptied by placing wafers onto the associated tracks; the wafers are then moved past the heating station synchronously, and are sequentially inserted into the receiving magazines at the discharge station. When the feed magazines are emptied, full magazines are substituted therefor; when the receiving magazines are filled. empty magazines are substituted therefor.

With respect to the illustrative track 6 shown in FIGS. 3 and 4, it will be noted that feed mechanism 11 and its associated feed magazine 16, and discharge mechanism 21 and itsassoeiated receiving magazine 26, are supported for opposite indexing downwardlly and upwardly respectively in conjunction with feeding and receiving of wafers in sequence onto and from track 6 during transportation thereof between the predetermined stations 2 and 4 mentioned previously. In that regard, details of construction of the indexing means utilized for sequentially and automatically indexing magazines 16 and 26 downwardly and upwardly have not been disclosed herein in detail because such indexing means have been known in the art heretofore, as illustrated, for example, in Lasch, Jr. et al. U.S. Pat. No. 3,645,581 and in Lasch, Jr. et al. application Ser. No. 404,287 filed Oct. 9, 1973.

For the present purposes, it should be understood that various known mechanisms (mechanical, pneumatic or hydraulic in operation, for example) may be utilized to sequentially index the feed magazine and receiving magazine utilized in conjunction with each track, so long as the indexing means chosen is capable of automatically responding to control signals indicating when a wafer should be fed from the feed magazine and when a wafer has been fed into the receiving magazine, so that each magazine may be suitably indexed following such outfeeding and infeeding.

As noted from FIG. 2, the respective tracks, feed mechanisms, discharge mechanisms, and associated wafer heating structure, as well as the belt actuating mechanism to be described, are all supported, preferably at table height, by a lower supporting framework, generally designated 31, which includes a plurality of depending legs 32 of desired length. Framework 31 includes a plurality of frame members 33 joined by welding or the like with each other and with the supporting legs 32 to provide a horizontal generally rectangular base for the operative components of the apparatus, collectively designated 34.

The respective tracks 6, 7, 8 and 9 extend longitudinally of base 34 and are supported thereby. In that regard, as seen from FIGS. 2 and 3, secured to each other and to the base 34 by welding or the like are a plurality of horizontal frame members 36 upon which the tracks are directly supported and between which the actuating mechanism for the belts are positioned.

Additional frame members extend upwardly from base 34 and are secured thereto by welding or the like, as also seen in FIGS. 2 and 3. Such upright frame members are designated 37 and are joined by welding or the like to additional horizontal frame members 38 positioned at vertically spaced locations as seen in FIG. 2 above the base 34. Thus, the upright frame members and horizontal frame members 37 and 38 provide mounting means for the wafer heating unit 41 to be described. Such horizontal and upright frame members also provide means for supporting an insulating enclosure for the heating unit, which surrounds the same substantially completely on all sides, and is designated 42 generally. Opposite longitudinal sides of the enclosures are designated 43, the top thereof is designated 44, and opposite ends are designated 46.

As best seen from FIGS. 2 and 3, the insulating enclosure 42 is supported by the upright and vertical frame members 37 and 38 so that limited clearance is provided above the respective tracks to permit wafers to pass over the tracks through narrow slots provided in the opposite end walls 46 thereof. Any suitable form of insulation may be utilized so long as the same is capable of withstanding and effectively retaining heat within enclosure 42 at the level generated by heater 41.

In that regard, as seen in the FIGS. 2 and 3, the heating unit 41 preferably is vertically adjustably supported by a plurality of supporting rods 47 depending from and supported by the upper framework described previously. A series of aperturcd plates 48 are secured to outer margins of the heating unit 41 with the supporting rods 47 passing therethrough. The supporting rods are threaded so that adjusting nuts 49 may be threaded to predetermined positions to locate the heating unit a predetermined distance above the tracks passing therebeneath to satisfy predetermined temperature requirements.

In that connection, any commercially available form of heating unit 41 may be utilized in the subject apparatus, depending upon the nature of the heat treating operation to be effected on the wafers passing therebeneath. Preferably, however, an infra-red radiation heater is utilized for applying a uniform area of radiant heat to wafers carried therebeneath. One such infra-red heater well suited for the stated purpose is identified as Triple Power Infra-Red Solar Heater" distributed by CassoSolor Corporation of Kew Gardens, New York. Such a heating unit comprises a quartz block in which heating elements are inlaid so their full heating power can be utilized to heat the quartz body in which the heating elements are embedded so that the quartz body transmits virtually all the energy created downwardly against the wafers to be heated thereby. Although the infra-red heater of the type described is preferred, the specific type of heating unit utilized may vary, depending upon heating requirements and manufacturing needs.

It should be understood, however, that the heating unit employed is positioned to overlie the major portion of the tracks between the feed magazines and dis charge magazines. In that regard, one elongated heating unit, or a plurality of two or more discrete heating unit sections combined to define a substantially continuous heating unit, may be utilized.

As mentioned previously, each of the plural tracks of the illustrated apparatus is defined by a combined fluid bearing structure positive drive pacing belt over which and by which a stream of spaced wafers is transported synchronously and sequentially beneath the heating unit 41.

Referring to FIGS. 2 and 3, the synchronous drive mechanism for the respective belts 56 of the apparatus is designated generally 57. Such synchronous drive mechanism 57 includes a pair of transversely extending parallel shafts 58 and 59 positioned adjacent the opposite infeed and outfeed ends of the apparatus. Each such shaft has mounted thereon a plurality of laterally spaced pulley wheels 61 and 62 around which the belts 56 pass, as will be described in greater detail hereinafter. Shaft 58 comprises the drive shaft of the belt drive mechanism and is positively actuated through a chainmotor drive. Such drive includes a chain 63 which passes around a toothed sprocket 64 secured to shaft 58 and a second toothed sprocket 66 driven by an electrical stepping motor of known design. Sprocket 66, chain 63 and sprocket 64 are rotated by the motor in predetermined stepped increments to correspondingly rotate drive shaft 58 and each of the plurality of belts 56 driven thereby in corresponding increments. That is,

upon rotation of sprocket 66 by stepping motor 67, the belts 56 of the respective tracks are moved synchronously and for uniform distances at uniform rates so that wafers positioned on the respective tracks are synchronously and simultaneously moved through the apparatus beneath the heating unit in step fashion.

Each of the shafts 58 and 59 is mounted for rotation at its opposite ends in a pair of opposed bearing blocks 68 and 69 for the stated purpose. Note FIG. 2 in that regard with respect to shaft 58.

As seen in FIG. 3, the stepping motor is operatively mounted in known fashion to a supporting plate 71 bolted or otherwise secured to a second supporting plate 72 depending from the aforementioned frame members 36 supported by base 34 of the apparatus.

To provide each belt 56 with its wafer pacing and spacing capability, means are provided at spaced locations thereon with which the respective wafers are engaged during movement through the apparatus. Such means regulate the speed of movement of individual wafers through the apparatus as the same are supported upon and moved longitudinally of the tracks by the fluid bearing structure of the tracks in the manner to be described. Such wafer spacing means, as best seen in FIGS. 3 and 5, comprises a series of spacer buttons each of which is designated 76 and each of which is defined by a metal (such as stainless steel) or temperature resistant plastic (such as Teflon or Kapton) pin 77 having a head 78 at one end thereof and a shank 79 which extends through an aperture provided in the belt 56. Each pin 77 is held in place by a metal or plastic sleeve 81 which surrounds shank 79 and is held in engagement with the shank by a spring washer 82, preferably of high temperature resistant metal or plastic, which passes over the end of pin shank 79 to hold the sleeve in place in engagement with the surface of the belt which is opposite from the surface with which pin head 78 is engaged.

The spacer buttons 76 constructed as described are positioned through spaced apertures provided in belt 56 at predetermined uniform locations along the belt.

Belt 56 preferably is formed from a high temperature material with a flexible plastic being preferred, although a high temperature metal, such as stainless steel could be employed. In that regard, it has been found that a non-metallic belt formed of Kapton polyamide plastic (produced and marketed by E. l. DuPont de Nemours Co.) is particularly well suited for the stated purpose because of its high temperature resistance and wide range of temperature utilization, ranging from -200C or lower to +400C or higher. In the present circumstances, wafer temperatures desirably reach +200C or more in conjunction with their heat treatment by the subject apparatus so that the Kapton material described is particularly well suited for the stated purpose.

In addition to providing means for spacing wafers at predetermined distances during their passage through the apparatus, the spacer buttons 76 also provide means for pacing the rate of movement of the wafers via the belt drive mechanism described previously. In that regard, each drive pulley 61 adjacent the discharge end of the apparatus is provided with a series of recesses 86 at spaced peripheral locations around its outer edge (as best seen in FIG. 3) contoured to receive therein the head 78 of each spacer button as a belt passes around such pulley 61. Thus, upon positive intermittent rotation of pulley 61 by shaft 58 as described previously, positive intermittent drive of an associated belt 56 is effected in accordance with the mode and rate of movement of shaft 58 by the stepping motor 67.

Therefore, as best seen from FIGS. 3 and 4, the respective spacer buttons 76 limit movement of the respective wafers passing through the apparatus in accordance with the speed of movement of the pacing belt. That is, each belt is actuated to impede or pace each wafer in accordance with the predetermined speed desired for wafer movement as transmitted by the belt drive mechanism to the belt. It should be understood that during such pacing by the belt, the wafers are supported upon and moved longitudinally of the track by the levitating and transporting effect of the fluid emanating from the fluid bearing structure which combines with the positive drive belt in defining each operating track.

In that connection, as seen in FIGS. 2 and 3, each wafer W moving along a track is supported slightly above the upper surface of the track during movement to prevent wafer damage and to permit, when desired, rotation of the individual wafers by the fluid bearing track structure in the manner to be described.

Details of the fluid bearing track structure are shown in conjunction with exemplary track 6 seen in FIGS. 3 and 4. Fluid bearing track structure 6 is of elongated configuration and, as seen in FIG. 1, extends the full longitudinal distance of the apparatus between the infeed and outfeed stations 2 and 4. To facilitate manufacture of the fluid bearing structure and to permit selective operation thereof in different sections of the track structure, the fluid bearing is produced, in the illustrated embodiment, in four structurally discrete but functionally cooperable sections 91, 92, 93 and 94. Such four sections are arranged as end to end continuations ofeach other as seen in FIGS. 4A and 4B. The opposite end sections 9] and 94 preferably constitute unidirectional sections and the central sections 92 and 93 preferably constitute bi-directional sections for the purpose to be described.

In that regard, as noted from FIGS. 4 and 6, fluid bearing track structure 6 comprises an elongated supporting plate 97 which extends the length of the apparatus and provides a mounting base for the fluid bearing track structure. Plate 97 may be formed as one elongated member or in cooperable segments, depending upon manufacturing limitations. In either event, plate 97 is operatively mounted between opposed longitudinally extending bracket members 98 and 99 which in turn are secured in a suitable fashion, such as by welding, to the frame members 36 described previously. Screw type fasteners 101 may be utilized for securing plate 97 between brackets 98 and 99 as seen in FIG. 6. The plate 97 may be formed of metal or temperature resistance plastic, with metal, such as stainless steel or high temperature aluminum or aluminum alloy, being preferred.

Plate 97 is formed with two parallel spaced elongated longitudinal slots 102 and 103 therein as seen in FIG, 6 for its full extent. Such slots preferably are symmetrically arranged on opposite sides of the longitudinal axis of the plate.

Extending longitudinally along its axis between the axes of shafts 58 and 59 mentioned previously, as best seen in FIGS. 3 and 6, plate 97 is also provided with a stepped slot 104 having a central depressed area 106,

the latter being adapted to receive therein the heads 78 of the pins of the spacer buttons 76. The shallower upper portion of slot 104 is adapted to receive therein the pacing belt 56 in such fashion that the upper surface of the belt 56 is depressed slightly relative to the upper surface 107 of the plate 97. Thus wafers W moving along the track are not in contact with a belt but have edge contact only with the spacer buttons carried by the belt. Plate 97, as seen in FIGS. 3 and 4, also is provided with a pair of slots 108 and 109 in line with the pulleys 61 and 62 about which the belt 56 passes. Such slots accommodate the upper portions of the pulleys as the same rotate relative to the plate.

As noted from FIGS. 3 and 4, the opposite end sections 91 and 94 of the fluid bearing track structure extend into and substantially entirely through the associated feed magazine 16 and discharge magazine 26. Each such magazine straddles the fluid bearing track structure to permit the upward and downward indexing of such magazines as mentioned previously. Such end sections of the fluid bearing track structure include electrical or pneumatic sensing means 110 and 110' for transmitting control signals to the magazines for effecting magazine indexing as required. Such magazine sensing control has been known heretofore as described in the previously identified Lasch, Jr. patent and application.

It should be understood that positioning of section 91 of the fluid bearing track structure within magazine 16 permits the directional fluid bearing to sequentially withdraw the lowermost wafer from the magazine when the magazine is properly indexed and to automatically transfer each such wafer sequentially over track section 91 onto track section 92. Similarly, at the opposite end ofthe apparatus the positioning oftrack section 94 into magazine 26 permits such section 94 to receive wafers in sequence from track section 93 and to sequentially insert the same directly into magazine 26 as the magazine is sequentially indexed into position.

The intermediate track sections 92 and 93 carry wafers generally beneath the heating unit 41 and, because of the bidirectional capability preferably imparted to such intermediate sections, effect rotation of such wafers as the same are passing beneath the heating unit to effect uniform heating thereof and to preclude the formation of hot spots on the wafers.

Except for the uni-directional and bi-directional distinctions of the track sections noted, each section is identically constructed as best seen in FIGS. 4 and 6. Guide rails 111 and 112 are provided along lateral margins of the fluid bearing track structure and in the embodiment illustrated preferably are defined by elongated strips of Kapton plastic of the type noted previously. Such guide rails are held in place between the plate 97 and the brackets 98 and 99 between which plate 97 is mounted. For wafers of smaller diameter such guide rails may be moved inwardly and clamped in place in the respective slots 102 and 103 as shown in dotted lines in FIG. 6.

The slots 102 and 103 are dimensioned to receive therein generally L-shaped track members designated 113 and 114 respectively. Such track members are formed in separate sections but as longitudinal continuations of each other, as seen from FIG. 4. Each such track member is provided with a longitudinal plenum recess 116 and 117 respectively for its full length. The respective track members are held in place in slots 102 and 103 by screw fasteners extending vertically therethrough into plate 97 at predetermined locations (not shown).

The plenums of the respective tracks are operatively connected with a source of fluid bearing material, such as the nitrogen gas mentioned previously, via recesses 118 and 119 (FIG. 6) provided at spaced locations through plate 97. Pneumatic fittings 121 and 122, having hoses 123 and 124 connected with a suitable source of nitrogen or other fluid bearing gas are engaged with the plate 97 in communication with the recesses 118 and 119. Thus, a wafer supporting fluid medium may be introduced into the plenums defined by track members 113 and 114 and therethrough into contact with wafers positioned on the tracks.

To impart directional flow to the suporting fluid introduced into the plenums of each track as described. flexible insert strips, designated 123 and 124, are interposed between the respective track members 113 and 114 and an adjacent wall of slots 102 and 103, as best seen in FIG. 6. Such insert strips preferably are formed in accordance with the teachings of Lasch, Jr. US. Pat. No. 3,718,371, and each is provided with a series of equidistant similarly contoured directional fluid passages 126 and 127, as best seen in FIGS. 7 and 8. Each such strip is formed with recesses 128 and 129 extending therethrough which adapt such strips to receive bearing fluid from the plenum provided by track members 113 and 114 and to introduce such bearing fluid into the directional fluid passages 126 and 127 to emanate therefrom as a layer of supporting fluid in the manner and for the purpose described in said Lasch, Jr. US. Pat. No. 3,718,37l.

In that regard, asnoted previously, the end sections 91 and 94 of the fluid bearing track structure are unidirectional as shown by the directional arrows in FIG. 4. Such uni-directional effect is produced by inserting each of the jet strips 123 and 124 with their directional fluid passages facing in the same direction. The central bi-directional track sections 92 and 93 are provided with their bi-directional capability by reversely orienting the jet strips 123 and 124 relative to each other so that the directional fluid passages therein face in opposite directions, as shown by the directional arrows in FIG. 4.

Thus, wafers moving along end track sections 91 and 94 move generally in a straight non-rotational fashion because streams of fluid emanating from the two jet strips 123 and 124 are directed in the same direction. However, wafers moving along the central track sections 92 and 93 move rotationally and longitudinally over the bi-directional track sections 92 and 93 because streams of fluid emanate in opposite directions from the jet strips. Thus, fluid striking the underside of a wafer positioned effects rotational movement of such wafer as seen in FIG. 4 by the directional arrows shown therein.

As noted, such rotation of the wafers as the same are being supported by and moved along the fluid bearing track structure is effected to insure uniform heating of wafers passing through the apparatus beneath heating unit 41. However, under selected circumstances, such wafer rotation may be eliminated if uneven heating of articles being treated is not a problem merely by positioning each of the jet strips 123 and 124 in central track sections 92 and 93 to extend in the same direction.

By regulating the speed of movement of each belt 56 the rate of movement of each wafer through the heating apparatus, and therefore its total heat treating or bake time, may be closely controlled. Different bake times may be achieved by varying the dwell time after each incremental feed movement of the belt is effected. In the illustrated embodiment, the stepping motor 67 utilized effects 120 degree rotational incremental movement of the belt before the motor halts for a predetermined time. Thus wafers entering beneath the heating unit at spaced intervals progress therethrough at a predetermined rate determined by the rate of belt movement. In a illustrative embodiment, approximately two seconds is utilized to move each wafer a 3V2 inches increment, with an intermediate dwell time being chosen as desired to meet particular needs. A control switch (not shown) of conventional construction may be selectively set to determine the aggregate time of bake for each wafer, within wide range limits of 40 seconds to 15 minutes, for example.

Additionally, because the fluid supporting nitrogen gas passes through the plenum defined by the fluid bearing track structure, (which is subjected to heat from heating unit 41 such gas becomes heated by the track structure. As a result the wafers are levitated and moved on hot nitrogen gas which further enhances temperature stabilization of the wafers being treated.

Also. if preferred, the nitrogen supply may be cut off during each wafer dwell period, thereby allowing individual wafers to settle upon the upper surface ofa track structure and to be heated directly by conduction from the track structure while the same is simultaneously being heated from above from the intra-red radiation source 41. Prior to movement of the pacing conveyor another next increment, gas is introduced under the wafers to levitate them prior to movement of the belt so that damage to the wafers due to sticking thereof to the track structure is obviated.

In the illustrated embodiment, the heating unit 41 preferably is 36 inches long and spans ten wafer dwell positions between the infeed and outfeed ends of the apparatus. I

To prevent wafers from entering beneath the heating unit during the time the pacing belt is moving, a known vacuum brake structure 131 is incorporated at the infeed end of the apparatus and is timed to release a wafer only during a dwell period of the pacing belt. Thus, wafers are allowed to sequentially enter the heating station and contact the first protruding spacer button prior to movement of the belt. When the belt moves, the fluid bearing track structure urges the wafer to follow the belt, thus allowing another spacer button to emerge from below the upper surface of the track to constrain a subsequent wafer entering from behind. Vacuum brake 131 is provided in conjunction with the aforemention sensor 110' as seen in FIGS. 3 and 4 and as will be described hereinafter with respect to FIG. 9.

A similar vacuum brake structure 132 is provided in conjunction with sensor 110 provided at the outfeed end of the apparatus as seen in FIGS. 3 and 4. Such vacuum brake halts wafers fed into the discharge magazine sequentially prior to indexing of the magazine.

Conventional control switches and timers may be utilized to permit selective variation of the dwell period of the pacing belt. Thus, due to the synchronization effected by the belt drive mechanism described previously, each of the multiple tracks of the subject apparaus are actuated simultaneously and sequentially to move a plurality of streams of wafers in equally spaced relationship to and past the heating station as described.

Reference is now directed to FIG. 9 for diagrammatic illustration .of the pneumatic system utilized with the illustrated four track apparatus.

Supporting fluid is introduced through a central supply line 136 from any suitable gas source and passes through a pressure regulator 137 into supply line 138 and therefrom into a series of branch supply lines 139, 140 and 141. Solenoid valves 142, 143 and 144, which are regulated by associated needle control valves 146, I47 and 148, control fluid pressure in branch supply lines 149, and 151 which are continuations of lines 139, 140 and 141. Supporting fluid may thus be introduced into the various track sections of each fluid hearing track structure.

A manifold 152 receives bearing fluid from supply line 151 and distributes the same through a series of conduits 154 to each of the plenums provided in the uni-directional fluid bearings in each of the end track sections 91 of the respective tracks 6, 7, 8 and 9.

Supply line 150 is connected through a T-joint 155 with a pair of manifolds 156 and 157 with a series of conduits 158 and 159 connected with the plenums provided in the bidirectional track sections 92 and 93 of tracks 6, 7, 8 and 9.

Finally, supply line 149 is connected through manifold 161 with each of the plenums in the other unidirectional end track sections 94 provided adjacent the discharge end of the apparatus.

As mentioned previously, at the infeed end of the apparatus each track is provided with a vacuum stop 131 to preclude introduction of a wafer prematurely into the heating zone. Each such vacuum stop is connected through a manifold 161 and cooperating conduit 162 through a control gate 163 with a suitable source of vacuum 164. Similarly, at the discharge end of the apparatus each of the aforementioned vacuum stops 132 is connected via manifold 166 and associated conduit 167 through a control gate 168 with the vacuum source 164. 1

Having thus made a full disclosure of the subject apparatus and method which incorporate and utilize a fluid bearing and positive drive conveyor system in conjunction with a heat source, reference is directed to the appended claims for the scope of protection to be afforded thereto.

1 claim: 1. Apparatus for transporting articles, such as semiconductor'wafers, past a treating station, comprising A. infeed means at an infeed station for introducing articles in sequence into said apparatus, B. means at a station adjacent said infeed station for treating articles presented thereto, C. conveyor track means for receiving articles in sequence from said infeed means and presenting the same in spaced sequence to said treating station, comprising 1. directional fluid bearing structure on which articles are supported and by which the articles are positively moved from said infeed station to and past said treating station,

2. an endless pacer belt having article spacers carried thereon for maintaining articles spaced during transport past said treating station and for pacing movement of such articles by restricting movement thereof under controlled conditions as the articles are supported and moved by said fluid bearing structure, and

3. mechanism for positively driving said belt in accordance with a predetermined rate schedule, and

D. means at a discharge station for receiving articles in sequence after the same have passed from said treating station.

2. The apparatus of claim 1 in which said treating means at said treating station comprises a heating unit positioned above said conveyor track means for heating articles transported therebeneath on said conveyor track means.

3. The apparatus of claim 1 in which said fluid hearing structure includes a bi-directional section at said heating station which introduces bearing fluid in opposite directions against said articles supported thereby to effect rotation of such articles as the same pass said treating station.

4. The apparatus of claim 1 in which said infeed means and said discharge means each comprises an indexable magazine for feeding and receiving, respectively, articles in sequence to and from said conveyor track means.

5. The apparatus of claim 1 in which said drive mech anism for said belt includes means for intermittently moving said belt so that said articles are discontinuously moved past said treating station on said conveyor track means.

6. The apparatus of claim 1 in which said conveyor track means includes plural fluid bearing structures and belts extending in parallel relationship past said treating station, and plural infeed means and discharge means for feeding and receiving articles to and from respective tracks of said plural conveyor track means.

7. The apparatus ofclaim 6 in which said drive mech anism of said conveyor track structure includes means for moving each of said belts in synchronism so that parallel aligned streams of spaced articles may be transported past said treating stationv 8. The apparatus of claim 7 in which said treating means at said treating station comprises a heating unit positioned above said plural fluid bearing structures and belts for heating articles transported thereon.

9. The apparatus of claim 8 in which each of said fluid bearing structures includes a bi-directional section at said heating station which introduces bearing fluid in opposite directions against said articles supported thereby to effect rotation of such articles as the same pass said treating station.

10. The apparatus of claim 1 in which said fluid bearing structure includes a slot extending logitudinally thereof within which said belt moves, said belt being positioned below the upper surface of said fluid bearing structure with only said spacers projecting thereabove so that said articles are free of contact with said belt during transport past said treating station.

11. Apparatus for uniformly heating semiconductor wafers and like articles during manufacturing procedures for semiconductor devices, comprising A. infeed means at an infeed station for introducing wafers in spaced sequence to a heating station,

B. a heating unit at said heating station for heat treating wafers presented thereto,

C. conveyor track means for receiving wafers in sequence from said infeed means and transporting the same in spaced sequence beneath said heating unit at said heating station, comprising 1. an elongated directional fluid bearing structure on which said wafers are supported and by which said wafers are positively moved from said infeed station to and past said heating unit,

2. an endless pacer belt extending longitudinally of said fluid bearing structure having wafer spacers carried thereby, against which individual wafers come in contact, for maintaining said wafers spaced in predetermined positions and for pacing movement of said wafers by restricting movement thereof under controlled conditions during such movement past said heating unit, and

3. mechanism for positively driving said belt relative to said heating unit at a predetermined rate, and

D. means at a discharge station adjacent said heating station for receiving heat treated wafers in sequence after the same have passed said heating unit.

12. The apparatus of claim 11 in which said heating unit comprises a radiant heat source which transmits a field of radiant energy directly onto the wafers moving therebeneath.

13. The apparatus of claim 11 in which said fluid bearing structure includes a bi-directional section beneath said heating unit which introduces bearing fluid in opposite directions against said wafers supported thereby to effect rotation of said wafers, as the wafers move past said heating unit, to insure uniform heating thereof.

14. The apparatus of claim 11 in which said belt driving mechanism includes means for intermittently moving said belt so that wafers paced thereby are discontinuously moved beneath said heating unit.

15. The apparatus of claim 11 in which said conveyor track means includes plural fluid bearing structures and plural belts associated therewith which extend in parallel relationship beneath said heating unit, and plural infeed means and plural discharge means for feeding and receiving wafers to and from respective tracks of said plural conveyor track means.

16. The apparatus of claim 15 in which said drive mechanism of said conveyor track structure includes means for moving all of said belts in synchronism so that parallel aligned streams of spaced wafers may be transported past said heating station.

17. The apparatus of claim 15 in which each of said fluid bearing structures includes a bi-directional section at said heating station which introduces bearing fluid in opposite directions against said wafers supported thereby to effect rotation of such wafers as the same pass said heating station.

18. A method of transporting articles to and past a treating station, comprising A. introducing articles in spaced sequence onto a fluid bearing structure,

B. introducing directional article supporting fluid through said fluid bearing structure and supporting said articles thereon while the same are moved by said article supporting fluid past said treating station, C. while said articles are supported by and moved on said supporting fluid positively restricting their movement to pace the rate of travel thereof past said treating station, and

D. discharging treated articles in spaced sequence from said treating station.

19. The method of claim 18 which further includes E. rotating each of said articles at said treating station by introducing oppositely directed streams of supporting fluid thereagainst.

20. The method of claim 18 which includes temporarily halting movement of said articles as the same pass said treating statin by moving the same in predetermined interrupted increments therepast.

21. The method of claim 18 which includes heat treating said articles at said treating station. I

22. The method of claim 21 in which said articles are radiantly heated from above at said treating station.

23. The method of claim 22 in which said articles are simultaneously heated from below while being radiantly heated from above.

24. A method of heat treating semiconductor wafers and like articles during manufacturing procedures for semiconductor devices, comprising A. introducing a stream of spaced wafers in sequence onto a fluid bearing structure,

B. introducing directional supporting fluid through said fluid bearing structure and suporting said wafers thereon while moving the same past a heat source,

C. subjecting said wafers in sequence and for predetermined times to said heat source by moving the same on said supporting fluid therepast,

D. while said wafers are supported on said supporting fluid positively restricting their movement to pace their rate of travel past-said heat source, and

E. discharging heat treated wafers in spaced sequence from said heat source.

25. The method of claim 24 which includes F. insuring uniform heating of said wafers by said heat source by rotating said wafers relative to said heat source during travel thereof.

26. The method of claim 25 in which said wafers are rotated by directing opposed streams of supporting fluid against opposite portions of said wafers while the same are levitated thereby.

27. The method of claim 24 which includes G. heating said supporting fluid in conjunction with introducing the same against said wafers to assist in heat treating said wafers.

28. The method of claim 27 which includes radiantly heated said wafers from above by said heat source while simultaneously heating said wafers from below by said heated supporting fluid.

29. Apparatus for transporting articles, such as semiconductor wafers, past a treating station, comprising A. plural infeed means at an infeed station for introducing rows of articles in sequence into said apparatus,

B. means at a station adjacent said infeed station for treating articles presented thereto,

C. plural conveyor track means for receiving said rows of articles in sequence from said infeed means and presenting the same in spaced sequence to said treating station, comprising 1. plural fluid bearing structure on which said rows of articles are supported and moved from said infeed station to and past said treating station,

2. plural endless belts, extending in parallel relationship relative to each other and to said plural fluid bearing structures, extending past said treating station in alignment with said plural in- 5 feed means, said belts pacing movement of said rows of articles as the articles are supported and moved by the respective fluid bearing structures associated with each said belt, and

3. mechanism for driving each said belt in accor- I I0 dance with a predetermined rate schedule, and- D. plural means at a discharge station for receiving said rows of articles in sequence from the respective tracks of said plural conveyor track means after such articles have passed said treating station. 30. The apparatus of claim 29 in which said drive mechanism of said conveyor track means includes means for moving each of said belts in synchronism so that parallel aligned rows of spaced articles may be transported to and past said treating station.

31. The apparatus of claim 30 in which said treating means at said treating station comprises a heating unit positioned above said plural fluid bearing strutures and said belts for heating said rows of articles transported thereon.

32. The apparatus of claim 31 in which each of said fluid bearing structures includes a bi-directional section at said heating station which introduces bearing fluid in opposite directions against said articles supported thereby to effect rotation of such articles as the same pass said treating station.

33. Apparatus for transporting articles, such as semiconductor wafers, past a treating station, comprising A. infeed means at an infeed station for introducing articles in sequence into said apparatus,

B.. means at a station adjacent said infeed station for treating articles presented thereto,

C. conveyor track means for receiving articles in sequence from said infeed means and presenting the same in spaced sequence to said treating station, comprising l. fluid bearing structure on which articles are supported and moved from said infeed station to and past said treating station,

2. a slot extending in said fluid bearing structure extending longitudinally thereof,

3. an endless belt having article spacers carried thereon for maintaining articles spaced during transport past said treating station and for pacing movement of such articles as the articles are supported and moved by said fluid bearing structure,

4. said belt being positioned in said slot below the upper surface of said fluid bearing track structure with only said spacers projecting thereabove so that said articles are free of contact with said belt during transport past said treating station. and

5. mechanism for positively driving said belt in accordance with a predetermined rate schedule, and

D. means at a discharge station for receiving articles in sequence after the same have passed from said treating station.

34. Apparatus for uniformly heating semiconductor wafers and like articles during manufacturing proce dures for semiconductor devices, comprising A. infeed means at an infeed station for introducing wafers in spaced sequence to a heating station,

B. a heating unit at a heating station for heat treating tive to said heating unit at a predetermined rate,

wafers presented thereto, and C. conveyor track means for receiving wafers in 88- D. means at a discharge station adjacent said heating quence from Said lnfeed means and transporting station for receiving heat treated wafers in sethe Samfi in Spaced Sequfince beneath Said heating quence after the same have passed said heating unit at said heating station, comprising unit. an elongated directional fluid bearing strucflire 3s. The apparatus ofclaim 34in which said belt driv- On which 531d wafers are Supported and by whlch ing mechanism includes means for intermittently movsaid wafers are moved from said infeed station to and past said heating unit,

2. said fluid bearing structure including a bi directional section beneath said heating unit which introduces bearing fluid in opposite directions against said wafers supported thereby to effect rotation of said wafers, as the wafers move past said heating unit, to insure uniform heating thereof,

ing said belt so that wafers paced thereby are discontinuously moved beneath said heating unit.

36. The apparatus of claim 34 in which said conveyor track means includes plural fluid bearing structures and le] relationship beneath said heating unit, and plural infeed means and plural discharge means for feeding and receiving wafers to and from the respective tracks of 3. an endless belt extending longitudinally of said 881d Plural conveyor track means fluid bearing structure having wafer spacers car- The apparatus of Claim 36 in which Said drive ried thereby, against which i di id l wafer mechanism of said conveyor track structure includes come in Contact, for mai t i i id wafers means for moving all of said belts in synchronism so spaced in predetermined positions during movethat parallel aligned rows of spaced wafers may be ment past said heating unit, and transported past said heating station. 4. mechanism for positively driving said belt rela plural belts associated therewith which extend in paral-v 

1. Apparatus for transporting articles, such as semiconductor wafers, past a treating station, comprising A. infeed means at an infeed station for introducing articles in sequence into said apparatus, B. means at a station adjacent said infeed station for treating articles presented thereto, C. conveyor track means for receiving articles in sequence from said infeed means and presenting the same in spaced sequence to said treating station, comprising
 1. directional fluid bearing structure on which articles are supported and by which the articles are positively moved from said infeed station to and past said treating station,
 2. an endless pacer belt having article spacers carried thereon for maintaining articles spaced during transport past said treating station and for pacing movement of such articles by restricting movement thereof under controlled conditions as the articles are supported and moved by said fluid bearing structure, and
 3. mechanism for positively driving said belt in accordance with a predetermined rate schedule, and D. means at a discharge station for receiving articles in sequence after the same have passed from said treating station.
 1. an elongated directional fluid bearing structure on which said wafers are supported and by which said wafers are positively moved from said infeed station to and past said heating unit,
 1. plural fluid bearing structure on which said rows of articles are supported and moved from said infeed station to and past said treating station,
 1. fluid bearing structure on which articles are supported and moved from said infeed station to and past said treating station,
 1. directional fluid bearing structure on which articles are supported and by which the articles are positively moved from said infeed station to and past said treating station,
 1. Apparatus for transporting articles, such as semiconductor wafers, past a treating station, comprising A. infeed means at an infeed station for introducing articles in sequence into said apparatus, B. means at a station adjacent said infeed station for treating articles presented thereto, C. conveyor track means for receiving articles in sequence from said infeed means and presenting the same in spaced sequence to said treating station, comprising
 1. an elongated directional fluid bearing structure on which said wafers are supported and by which said wafers are moved from said infeed station to and past said heating unit,
 2. said fluid bearing structure including a bi-directional section beneath said heating unit which introduces bearing fluid in opposite directions against said wafers supported thereby to effect rotation of said wafers, as the wafers move past said heating unit, to insure uniform heating thereof,
 2. a slot extending in said fluid bearing structure extending longitudinally thereof,
 2. an endless pacer belt extending longitudinally of said fluid bearing structure having wafer spacers carried thereby, against which individual wafers come in contact, for maintaining said wafers spaced in predetermined positions and for pacing movement of said wafers by restricting movement thereof under controlled conditions during such movement past said heating unit, and
 2. The apparatus of claim 1 in which said treating means at said treating station comprises a heating unit positioned above said conveyor track means for heating articles transported therebeneath on said conveyor track means.
 2. an endless pacer belt having article spacers carried thereon for maintaining articles spaced during transport past said treating station and for pacing movement of such articles by restricting movement thereof under controlled conditions as the articles are supported and moved by said fluid bearing structure, and
 2. plural eNdless belts, extending in parallel relationship relative to each other and to said plural fluid bearing structures, extending past said treating station in alignment with said plural infeed means, said belts pacing movement of said rows of articles as the articles are supported and moved by the respective fluid bearing structures associated with each said belt, and
 3. mechanism for driving each said belt in accordance with a predetermined rate schedule, and D. plural means at a discharge station for receiving said rows of articles in sequence from the respective tracks of said plural conveyor track means after such articles have passed said treating station.
 3. mechanism for positively driving said belt relative to said heating unit at a predetermined rate, and D. means at a discharge station adjacent said heating station for receiving heat treated wafers in sequence after the same have passed said heating unit.
 3. The apparatus of claim 1 in which said fluid bearing structure includes a bi-directional section at said heating station which introduces bearing fluid in opposite directions against said articles supported thereby to effect rotation of such articles as the same pass said treating station.
 3. mechanism for positively driving said belt in accordance with a predetermined rate schedule, and D. means at a discharge station for receiving articles in sequence after the same have passed from said treating station.
 3. an endless belt having article spacers carried thereon for maintaining articles spaced during transport past said treating station and for pacing movement of such articles as the articles are supported and moved by said fluid bearing structure,
 3. an endless belt extending Longitudinally of said fluid bearing structure having wafer spacers carried thereby, against which individual wafers come in contact, for maintaining said wafers spaced in predetermined positions during movement past said heating unit, and
 4. said belt being positioned in said slot below the upper surface of said fluid bearing track structure with only said spacers projecting thereabove so that said articles are free of contact with said belt during transport past said treating station, and
 4. mechanism for positively driving said belt relative to said heating unit at a predetermined rate, and D. means at a discharge station adjacent said heating station for receiving heat treated wafers in sequence after the same have passed said heating unit.
 4. The apparatus of claim 1 in which said infeed means and said discharge means each comprises an indexable magazine for feeding and receiving, respectively, articles in sequence to and from said conveyor track means.
 5. The apparatus of claim 1 in which said drive mechanism for said belt includes means for intermittently moving said belt so that said articles are discontinuously moved past said treating station on said conveyor track means.
 5. mechanism for positively driving said belt in accordance with a predetermined rate schedule, and D. means at a discharge station for receiving articles in sequence after the same have passed from said treating station.
 6. The apparatus of claim 1 in which said conveyor track means includes plural fLuid bearing structures and belts extending in parallel relationship past said treating station, and plural infeed means and discharge means for feeding and receiving articles to and from respective tracks of said plural conveyor track means.
 7. The apparatus of claim 6 in which said drive mechanism of said conveyor track structure includes means for moving each of said belts in synchronism so that parallel aligned streams of spaced articles may be transported past said treating station.
 8. The apparatus of claim 7 in which said treating means at said treating station comprises a heating unit positioned above said plural fluid bearing structures and belts for heating articles transported thereon.
 9. The apparatus of claim 8 in which each of said fluid bearing structures includes a bi-directional section at said heating station which introduces bearing fluid in opposite directions against said articles supported thereby to effect rotation of such articles as the same pass said treating station.
 10. The apparatus of claim 1 in which said fluid bearing structure includes a slot extending logitudinally thereof within which said belt moves, said belt being positioned below the upper surface of said fluid bearing structure with only said spacers projecting thereabove so that said articles are free of contact with said belt during transport past said treating station.
 11. Apparatus for uniformly heating semiconductor wafers and like articles during manufacturing procedures for semiconductor devices, comprising A. infeed means at an infeed station for introducing wafers in spaced sequence to a heating station, B. a heating unit at said heating station for heat treating wafers presented thereto, C. conveyor track means for receiving wafers in sequence from said infeed means and transporting the same in spaced sequence beneath said heating unit at said heating station, comprising
 12. The apparatus of claim 11 in which said heating unit comprises a radiant heat source which transmits a field of radiant energy directly onto the wafers moving therebeneath.
 13. The apparatus of claim 11 in which said fluid bearing structure includes a bi-directional section beneath said heating unit which introduces bearing fluid in opposite directions against said wafers supported thereby to effect rotation of said wafers, as the wafers move past said heating unit, to insure uniform heating thereof.
 14. The apparatus of claim 11 in which said belt driving mechanism includes means for intermittently moving said belt so that wafers paced thereby are discontinuously moved beneath said heating unit.
 15. The apparatus of claim 11 in which said conveyor track means includes plural fluid bearing structures and plural belts associated therewith which extend in parallel relationship beneath said heating unit, and plural infeed means and plural discharge means for feeding and receiving wafers to and from respective tracks of said plural conveyor track means.
 16. The apparatus of claim 15 in which said drive mechanism of said conveyor track structure includes means for moving all of said belts in synchronism so that parallel aligned streams of spaced wafers may be transported past said heating station.
 17. The apparatus of claim 15 in which each of said fluid bearing structures includes a bi-directional section at said heating station which introduces bearing fluid in opposite directions against said wafers supported thereby to effect rotation of such wafers as the same pass said heating station.
 18. A method of transporting articles to and past a treating station, comprising A. introducing articles in spaced sequence onto a fluid bearing structure, B. introducing directional article supporting fluid through said fluid bearing structure and supporting said articles thereon while the same are moved by said article supporting fluid past said treating station, C. while said articles are supported by and moved on said supporting fluid positively restricting their movement to pace the rate of travel thereof past said treating station, and D. discharging treated articles in spaced sequence from said treating station.
 18. A method of transporting articles to and past a treating station, comprising A. introducing articles in spaced sequence onto a fluid bearing structure, B. introducing directional article supporting fluid through said fluid bearing structure and supporting said articles thereon while the same are moved by said article supporting fluid past said treating station, C. while said articles are supported by and moved on said supporting fluid positively restricting their movement to pace the rate of travel thereof past said treating station, and D. discharging treated articles in spaced sequence from said treating station.
 19. The method of claim 18 which further includes E. rotating each of said articles at said treating station by introducing oppositely directed streams of supporting fluid thereagainst.
 20. The method of claim 18 which includes temporarily halting movement of said articles as the same pass said treating station by moving the same in predetermined interrupted increments therepast.
 21. The method of claim 18 which includes heat treating said articles at said treating station.
 22. The method of claim 21 in which said articles are radiantly heated from above at said treating station.
 23. The method of claim 22 in which said articles are simultaneously heated from below while being radiantly heated from above.
 24. A method of heat treating semiconductor wafers and like articles during manufacturing procedures for semiconductor devices, comprising A. introducing a stream of spaced wafers in sequence onto a fluid bearing structure, B. introducing directional supporting fluid through said fluid bearing structure and supporting said wafers thereon while moving the same past a heat source, C. subjecting said wafers in sequence and for predetermined times to said heat source by moving the same on said supporting fluid therepast, D. while said wafers are supported on said supporting fluid positively restricting their movement to pace their rate of travel past said heat source, and E. discharging heat treated wafers in spaced sequence from said heat source.
 25. The method of claim 24 which includes F. insuring uniform heating of said wafers by said heat source by rotating said wafers relative to said heat source during travel thereof.
 26. The method of claim 25 in which said wafers are rotated by directing opposed streams of supporting fluid against opposite portions of said wafers while the same are levitated thereby.
 27. The method of claim 24 which includes G. heating said supporting fluid in conjunction with introducing the same against said wafers to assist in heat treating said wafers.
 28. The method of claim 27 which includes radiantly heated said wafers from above by said heat source while simultaneously heating said wafers from below by said heated supporting fluid.
 29. Apparatus for transporting articles, such as semiconductor wafers, past a treating station, comprising A. plural infeed means at an infeed station for introducing rows of articles in sequence into said apparatus, B. means at a station adjacent said infeed station for treating articles presented thereto, C. plural conveyor track means for receiving said rows of articles in sequence from said infeed means and presenting the same in spaced sequence to said treating station, comprising
 30. The apparatus of claim 29 in which said drive mechanism of said conveyor track means includes means for moving each of said belts in synchronism so that parallel aligned rows of spaced articles may be transported to and past said treating station.
 31. The apparatus of claim 30 in which said treating means at said treating station comprises a heating unit positioned above said plural fluid bearing structures and said belts for heating said rows of articles transported thereon.
 32. The apparatus of claim 31 in which each of said fluid bearing structures includes a bi-directional section at said heating station which introduces bearing fluid in opposite directions against said articles supported thereby to effect rotation of such articles as the same pass said treating station.
 33. Apparatus for transporting articles, such as semiconductor wafers, past a treating station, comprising A. infeed means at an infeed station for introducing articles in sequence into said apparatus, B. means at a station adjacent said infeed station for treating articles presented thereto, C. conveyor track means for receiving articles in sequence from said infeed means and presenting the same in spaced sequence to said treating station, comprising
 34. Apparatus for uniformly heating semiconductor wafers and like articles during manufacturing procedures for semiconductor devices, comprising A. infeed means at an infeed station for introducing wafers in spaced sequence to a heating station, B. a heating unit at a heating station for heat treating wafers presented thereto, C. conveyor track means for receiving wafers in sequence from said infeed means and transporting the same in spaced sequence beneath said heating unit at said heating station, comprising
 35. The apparatus of claim 34 in which said belt driving mechanism includes means for intermittently moving said belt so that wafers paced thereby are discontinuously moved beneath said heating unit.
 36. The apparatus of claim 34 in which said conveyor track means includes plural fluid bearing structures and plural belts associated therewith which extend in parallel relationship beneath said heating unit, and plural infeed means and plural discharge means for feeding and receiving wafers to and from the respective tracks of said plural conveyor track means. 